1. Field of the Invention
The present invention relates generally to facsimile devices and, more particularly, to a facsimile device having an automatic receiving function.
2. Description of the Background Art
Facsimile devices serve as still-picture transmit/receive apparatus for transmitting/receiving via telephone lines a picture signal obtained by decomposing characters, figures, photographs, etc. into a plurality of small pixels by scanning and are in wide use. The facsimile devices are connected with each other via telephone lines through a switchboard. When one of the two facsimile devices connected via telephone lines through the switchboard transmits a picture signal to the other device, the one facsimile device supplies a signal indicating a request-to-send as an output to the switchboard. In response to this applied signal, the switchboard transmits a signal for ringing the bell of a telephone for general use (hereinafter referred to as ringing signal) to the other facsimile device. The facsimile device is connected with the telephone for general use, so that the bell of the connected telephone rings in response to the ringing signal from the switchboard.
There are two or more types of facsimile devices: one has both an automatic receive mode, in which the facsimile device can automatically receive a picture signal in response to a ringing signal from the switchboard, and a manual receive mode, in which the facsimile device is set to be able to receive a picture signal by manual operation of users responding to a ring of the bell of a telephone connected to the device; and the other has only the manual receive mode.
FIG. 6 is a schematic block diagram showing general structure of a conventional facsimile device having an automatic receiving function. With reference to FIG. 6, a controller 100 includes a main controller 110, an image memory controller 120, an image memory 130, a sensor circuit 140, a panel controller 150, a mechanism/record controller 160, a read processor 180, a transmission controller 4, and a ringing signal detecting circuit 5.
An operation panel 8b includes a keying switch, by which users perform mode setting of this facsimile device, starting of transmission/reception and the like, and a display panel for displaying various information for the users' operation. A network control unit (hereinafter referred to as NCU) 2 serves as an interface for coupling lines 1 and the facsimile device. A modem 3 has a function of receiving a picture signal transmitted via lines 1 through NCU 2 and then demodulating the received picture signal in the form of a signal that can be processed in controller 100, i.e., a digital signal, and a function of modulating a picture signal to be transmitted in a signal form that is suitable for transmission via lines 1. An original feeding system 210 serves to feed originals such as paper, on which characters and figures or designs to be transferred are drawn, and photographs into the facsimile device. A lighting system 190 is supplied with power from a lighting circuit 170, to light up the original fed into the facsimile device by original feeding system 210. Reflected light from the original, caused by this lighting up, enters in a read optical system 200. Read optical system 200 includes an image sensor formed such as of CCD (Charge-Coupled Device) image sensing devices. The reflected light from the original forms an optical image of the figures or designs on the original onto a light receiving surface of the image sensor. Thus, read optical system 200 supplies as an output an analog picture signal of one picture frame corresponding to the figures or designs on the original. A recording system 210 serves to print the figures or designs, corresponding to the picture signal received by the facsimile device, on record paper and then to transmit the printed record paper outside the facsimile device. In general, original feeding system 210 includes various sensors for detecting positions of the original, or the like. Similarly, recording system 220 includes sensors for detecting positions of the record paper, or the like.
Sensor circuit 140 supplies information based on output signals of the sensors included in the original feeding system 210 and recording system 220 to main controller 110. Panel controller 150 detects a key entry into operation panel 8b and supplies the detected key entry to main controller 110, and also changes displays on operation panel 8b in response to an instruction from main controller 110. Read processor 180 serves to subject a picture signal in analog form, supplied as an output from read optical system 200, to a predetermined correction processing. Image memory controller 120 serves to convert the picture signal subjected to the correction processing by read processor 180 into image data of a predetermined form and to supply the image data to image memory 130. Image memory 130 stores the image data supplied by image memory controller 120. Image memory controller 120 further reads the image data from image memory 130 and converts the read image data into a picture signal of the original form, to supply the converted signal to main controller 110 and transmission controller 4. Mechanism/record controller 160 controls mechanical operations such as of original feeding system 210 and recording system 220, so that the travelling of the original and record paper, the density of printing onto the record paper, etc. may be appropriate.
In transmission, since a picture signal of the original is supplied as an output from read optical system 200, image data corresponding to this picture signal is once stored in image memory 130, then read and applied to image memory controller 120. Transmission controller 4 provides a processing for transmission (encoding processing) to the picture signal supplied by image memory controller 120 and then applies the processed picture signal to modem 3. Main controller 110 carries out a control for this operation of transmission controller 4 in response to the picture signal supplied as an output from image memory controller 120. As a result, a picture signal corresponding to the figures or designs on the original is transmitted via modem 3 and NCU 2 onto lines 1.
In reception, since a picture signal is supplied as an input to NCU 2 via lines 1, transmission controller 4 provides an opposite processing (decoding) from the foregoing processing for transmission to a picture signal demodulated by modem 3. The picture signal processed by transmission controller 4 is applied to image memory controller 120. Accordingly, image data corresponding to the picture signal received by this facsimile device is stored in image memory 130. The image data stored in image memory 130 at this time is restored to the original picture signal by image memory controller 120 and the restored signal is applied to main controller 110. Main controller 110 controls mechanism/record controller 160 in response to the picture signal supplied by image memory controller 120 at this time so that figures or designs corresponding to the received picture signal may be printed on record paper in recording system 220.
Main controller 110 controls, in practice, the operation of all function portions included in controller 100, and a power supply circuit 230. Power supply circuit 230 is controlled by main controller 110 so as to convert an alternating voltage applied from a power supply for commercial use into a predetermined direct current voltage and to apply the converted voltage to an internal circuit of the facsimile device including controller 100.
In order that the facsimile device becomes the above-described receiving state, a ringing signal from a switchboard (not shown) must be applied via lines 1 to NCU 2. FIG. 9 is a diagram showing a general waveform of this ringing signal.
With reference to FIG. 9, this ringing signal has a definite frequency fc, a duration Tc and a rest period Tb. The conventional facsimile device having automatic receiving function stores in advance the characteristics of a ringing signal (frequency, duration, rest period, etc.) employed for lines connected with this facsimile device. When a signal having the same characteristics as those already stored in the device is supplied as an input, the facsimile device determines that there is a ringing, and thus performs a facsimile receiving operation.
That is, referring to FIG. 6, main controller 110 is constituted, in general, by a CPU (Central Processing Unit) including a memory. Patterns of the characteristics of the ringing signal employed for the lines are fixedly stored in this memory in advance.
A ringing signal transmitted from the switchboard is applied via NCU 2 to ringing signal detecting circuit 5.
FIG. 7 is a circuit diagram showing one example of ringing signal detecting circuit 5 employed in the conventional facsimile device having automatic receiving function. FIG. 8 is a diagram showing signal waveforms appearing in the circuit shown in FIG. 7. It is assumed, for example, that a ringing signal having a waveform shown in FIG. 8 (a) is supplied as an input to this ringing signal detecting circuit. This supplied ringing signal is an alternate current signal of 75 V, 16 Hz, which is superimposed on DC48V, a direct current voltage of line 1. A condenser 41 serves to block a direct current component of DC48V of a voltage signal applied via line 1 and to extract only an alternate current component of 16 Hz shown in FIG. 8 (b). The alternate current component extracted by condenser 41 is subjected to half-wave rectification by diodes 42 and 43. This causes a signal having a waveform shown in FIG. 8 (c) to be applied to a light emitting diode 441 in a photocoupler 44. A light receiving transistor 442 in photocoupler 41 is rendered conductive in response to light emitted from light emitting diode 441, to apply an output voltage of a reference voltage source 46 to an amplifying/inverting circuit 45. Therefore, the signal subjected to the half-wave rectification by diodes 42 and 43 is applied through photocoupler 44 to amplifying/inverting circuit 45. Amplifying/inverting circuit 45 includes two NPN transistors 451 and 452 in Darlington connection. These transistors 451 and 452 invert an input signal to be applied amplifying/inverting circuit 45 and then provide a rectangular wave of 16 Hz as shown in FIG. 8 (d) to an output terminal of amplifying/inverting circuit 45.
Referring to FIG. 6 again, main controller 110 determines the characteristics of a ringing signal (frequency, duration, rest period, etc.) in response to the signal having the rectangular wave detected from ringing signal detecting circuit 5 as described above. When the pattern of the determined characteristics is identical to that of the ringing signal already stored in the memory of main controller 110, main controller 110 determines that there is a ringing and then initiates a series of control operations for receiving a picture signal.
As described above, the conventional facsimile device should fixedly store, in advance, the characteristic pattern of a ringing signal on the lines connected with the facsimile device (hereinafter referred to as a match pattern). The ringing signal shown in FIG. 8 (a) is employed in public telecommunication lines in Japan. The characteristics of ringing signals are different for each country. FIG. 10 is a diagram showing an example of ringing signals having different characteristics employed in different countries. As shown in this diagram, the characteristics of the ringing signals vary in different countries. Thus, an individual match pattern, corresponding to each area where each facsimile device is installed, should be stored in a memory of a CPU or the like in each facsimile device, in the manufacture of the facsimile devices. Thus, the facsimile devices must be manufactured individually for their installation destinations. Therefore, the conventional facsimile device is disadvantageous with respect to its low production efficiency.
In addition, facsimile devices are not only connected directly to such public telecommunication lines but also to private branch exchanges (hereinafter referred to as PBX). For example, when a plurality of telecommunication devices share one public telecommunication line in a company and the like, an employed PBX is connected via the public line to a switchboard in a telecomunnication station, but via separate lines to those telecommunication devices. When a ringing signal is transmitted from the switchboard in the station onto the public line, the PBX transmits a ringing signal to any of the of telecommunication devices in response to the transmission of the ringing signal to the public line. Therefore, a match pattern corresponding to the ringing signal of the PBX must be stored in advance in a facsimile device connected to the PBX. There are, however, numerous types of ringing signals of the PBXs depending on the type of the PBXs or the like. Thus, it is very difficult as a practical matter to manufacture the facsimile devices having automatic receiving function separately according to different types of the PBXs connected with the devices. Moreover, the PBXs has been increasingly improved recently. Thus, there are some ringing signals of the PBXs that cannot be known to manufacturers these days. Therefore, there is another problem that a match pattern to be stored in advance in a facsimile device cannot be determined.